JP2005241918A - Printer and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To print at a high speed while deterring an image printed by a color printer from being uneven. <P>SOLUTION: Four image forming units 3a to 3d for yellow, magenta, black, and cyan are provided around a photoreceptor drum 22 of the printer 1 in order in the turning direction of the photoreceptor drum 22. The image forming units 3a to 3d have chargers 31a to 31d, image formation parts 32a to 32d and developing units 33a to 33d respectively. Consequently, an electrostatic latent image formed when toner of cyan is imparted is still charged in a place where toner of black sticks on the photoreceptor 222 and then a little toner of cyan sticks on the toner of black. Consequently, high-speed printing can be performed while the printed image is deterred from being uneven as compared with a case wherein development of black is finally performed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for printing an image on a print medium.

There is an electrophotographic printing apparatus that forms an electrostatic latent image by irradiating a charged photoreceptor with image forming light, and transfers the toner applied on the electrostatic latent image to printing paper to print the image. It has been used in various fields. For example, four developing units that respectively apply a developer containing yellow (Y), magenta (M), cyan (C), and black (K) toners to the surface of the photosensitive member are arranged around one photosensitive drum. It is arranged in the order of Y, M, C, K in the rotation direction, and each developing device applies a developing solution to the electrostatic latent image formed according to the color of the toner and develops it, thereby developing a color image at high speed. 2. Description of the Related Art A color printing apparatus that prints on an image is known (for example, see Patent Document 1).
JP 2001-92261 A

  By the way, in the type of printing apparatus in which each color developing device is arranged around one photosensitive drum as in the color printing apparatus described above, yellow, magenta, and cyan images are formed on the photosensitive body in consideration of color reproducibility. Is developed, an electrostatic latent image showing a black component is formed. However, the transmittance of toner of at least one of yellow, magenta, and cyan is low in the practical wavelength range of image forming light. It is common. Therefore, depending on the intensity of light for black image formation, the photosensitive state may become unstable at the site on the photoreceptor where the toner having a low transmittance at that wavelength adheres, and the printed image may become uneven. Further, black toner adhering to yellow, magenta, and cyan toners has a great influence on the hue of the image, and when black is uneven, the image has a very large contrast.

  Therefore, conventionally, when forming an electrostatic latent image showing a black component, the output of the light source (light emitting element) and the exposure time have been sufficiently increased in order to ensure a constant exposure amount. Since the output of the light emitting element is limited, another expensive light source is required to further reduce the exposure time. One solution may be to improve the spectral transmission characteristics of the toner without affecting the chromaticity, but the development of such a toner is not easy.

  The present invention has been made in view of the above problems, and an object of the present invention is to perform high-speed printing while suppressing occurrence of unevenness in an image printed in a color printing apparatus.

  The invention according to claim 1 is a printing apparatus, wherein a first image forming unit that forms a first electrostatic latent image by irradiating light to a charged photoconductor, and the first static image on the photoconductor. A first developing device for applying black toner to the electrostatic latent image and developing; a charging device for applying charge to the photoconductor after development by the first developing device; and the photoconductor after charging by the charger. A second image forming unit that irradiates light to form a second electrostatic latent image, and the first image forming unit out of cyan, magenta, and yellow toners on the second electrostatic latent image on the photoreceptor. A second developing device that applies and develops toner of one color whose light transmittance is 30% or less, and a mechanism that transfers the toner on the photoconductor to a printing medium.

  A second aspect of the present invention is the printing apparatus according to the first aspect, wherein the wavelength of light from the first image forming unit is 520 nm or more, and the one color is cyan.

  A third aspect of the present invention is the printing apparatus according to the first aspect, wherein the wavelength of light from the first image forming unit is 480 nm or more and 620 nm or less, and the one color is magenta.

  A fourth aspect of the present invention is the printing apparatus according to the first aspect, wherein the wavelength of light from the first image forming unit is 500 nm or less, and the one color is yellow.

  A fifth aspect of the present invention is the printing apparatus according to any one of the second to fourth aspects, wherein the transmittance of light from the first image forming unit of the toner of the one color is 20% or less. is there.

  The invention according to claim 6 is a printing apparatus, wherein the charged photosensitive member is irradiated with red or infrared light to form a first electrostatic latent image, and on the photosensitive member. A first developing device for applying black toner to the first electrostatic latent image and developing the first electrostatic latent image; a charging device for applying a charge to the photoconductor after development by the first developing device; and charging by the charging device. A second image forming unit that forms a second electrostatic latent image by irradiating light to the subsequent photoconductor, and cyan toner that is one color is applied to the second electrostatic latent image on the photoconductor And a second developing device for developing, and a mechanism for transferring the toner on the photosensitive member to a printing medium.

  The invention according to claim 7 is a printing apparatus, wherein the charged photoconductor is irradiated with green light to form a first electrostatic latent image, and the first image forming unit on the photoconductor. A first developing unit that applies black toner to the electrostatic latent image for development; a charging unit that applies a charge to the photoreceptor after development by the first developing unit; and the charging unit that is charged by the charging unit. A second image forming unit for irradiating the photosensitive member with light to form a second electrostatic latent image, and developing the second electrostatic latent image on the photosensitive member by applying a magenta toner as one color. And a mechanism for transferring the toner on the photoreceptor to a printing medium.

  The invention according to claim 8 is the printing apparatus according to any one of claims 1 to 7, wherein the first image data indicating a black component of an image to be printed and the first color component indicating the one color component. An arithmetic unit that corrects the second image data based on two image data and sets a region on the photosensitive member irradiated with light from the first image forming unit as a non-irradiated region of light from the second image forming unit Is further provided.

  A ninth aspect of the present invention is the printing apparatus according to any one of the first to eighth aspects, wherein the toner used for development is a wet toner.

  The invention according to claim 10 is a printing method for printing an image, wherein a first electrostatic latent image is formed by irradiating a charged photosensitive member with light from a first image forming unit, and the photosensitive member. A step of applying black toner to the first electrostatic latent image above and developing, a step of applying charge to the photoconductor after development and charging, and a second image formation on the photoconductor after charging Irradiating light from a portion to form a second electrostatic latent image, and light from the first image forming portion among cyan, magenta, and yellow toners on the second electrostatic latent image on the photoreceptor. A step of applying and developing one color toner having a transmittance of 30% or less, and a step of transferring the toner on the photoconductor to a printing medium.

  According to the first to tenth aspects of the present invention, printing can be performed at high speed while suppressing the occurrence of unevenness in the image.

  In the invention of claim 8, the occurrence of unevenness can be further suppressed.

  FIG. 1 is a diagram showing a configuration of a printing apparatus 1 according to an embodiment of the present invention. The printing apparatus 1 includes a photosensitive drum 22 connected to a motor 21 via a speed reducer, a belt, and the like, and the photosensitive drum 22 is supported so as to be rotatable about a central axis J1 in FIG. The photosensitive drum 22 includes a cylindrical member 221 that is formed of metal and has a central axis J1 as the center, and the cylindrical member 221 is electrically grounded. The photosensitive member 222 is uniformly applied (or deposited) on the outer peripheral surface of the cylindrical member 221.

  Around the photosensitive drum 22, four image forming units 3a, 3b, 3c, and 3d are sequentially provided in the clockwise direction. The image forming units 3a to 3d include chargers 31a to 31d that generate ions to give charges to the photosensitive member 222, and light sources (for example, light emitting diodes (LEDs)) that emit red light having a wavelength of 700 nm. Image forming units 32a to 32d that form an electrostatic latent image by irradiating light to the subsequent photosensitive member 222, and a developing device that applies wet toner to the electrostatic latent image formed on the photosensitive member 222 for development. 33a to 33d are sequentially provided in the clockwise direction (that is, along the rotation direction of the photosensitive drum 22). The four image forming units 3a to 3d are for yellow, magenta, black and cyan, respectively, and the developing devices 33a to 33d hold yellow, magenta, black and cyan toners, respectively. In the following description, the formation of electrostatic latent images in each of the image forming units 3a to 3d and the development of the electrostatic latent images are collectively referred to as image formation with toner.

  Around the photosensitive drum 22, a transfer mechanism 34 for transferring the toner on the photosensitive member 222 to the printing paper 9 and a cleaner 35 for cleaning the surface of the photosensitive member 222 are arranged. The transfer mechanism 34 includes a transfer drum 341 that rotates while being in contact with the photosensitive drum 22, and a pressure drum 342 that is rotated while being in contact with the transfer drum 341. The toner on the photoreceptor 222 is transferred to the surface of the transfer drum 341, and the toner on the transfer drum 341 is fixed onto the printing paper 9 by the pressure drum 342 while being transferred onto the printing paper 9.

  The printing apparatus 1 further includes a control unit 4 to which image data is input from the outside. In the printing apparatus 1, an image is printed on the printing paper 9 by the control unit 4 controlling each configuration based on the image data. The calculation unit 41 of the control unit 4 generates data used for drawing by the image forming units 32a to 32d from the image data.

  2 and 3 are diagrams illustrating a flow of processing in which the printing apparatus 1 prints an image on the printing paper 9. Actually, steps S13 to S15, S16 to S18, S21 to S23, and S24 to S26 are partially performed in parallel.

  In the printing apparatus 1, first, color image data is input from the outside to the control unit 4, and image data indicating yellow, magenta, black, and cyan components is generated and prepared by the calculation unit 41 (step S <b> 11). . Note that image data of each color component may be directly input to the control unit 4. Subsequently, by driving the motor 21, the photosensitive drum 22 starts rotating clockwise about the central axis J1 (that is, the rotation direction indicated by the arrow 71 in FIG. 1) (step S12). As a result, the photosensitive member 222 continuously moves with respect to each peripheral configuration (that is, the image forming units 3a to 3d, the transfer mechanism 34, and the cleaner 35) arranged around the photosensitive member 222. Processing begins.

  First, an image of yellow toner is formed on a part of the photoreceptor 222 (hereinafter referred to as “target portion”) that reaches a position facing the image forming unit 3a (that is, formation of an electrostatic latent image). And development is performed). Specifically, after charging the target site by the charger 31a (step S13), light for image formation is directed to the target site from the image forming unit 32a controlled based on the image data indicating the yellow component. Emitted. The charge on the surface of the target portion of the photosensitive member 222 irradiated with light moves into the photosensitive member 222 and is removed. In addition, since the charged state is maintained as it is in the portion that is not irradiated with light, an image (that is, an electrostatic latent image) is formed on the surface of the photoreceptor 222 due to the distribution of charges (step S14). The portion (target portion) where the electrostatic latent image indicating the yellow component is formed moves to a position facing the developing device 33a, and the charged yellow toner (more precisely, the toner diffused in the solvent) is electrostatically charged. It is given to the latent image (step S15). The yellow toner adheres only to the portion of the photosensitive member 222 where the charge has been removed, and the electrostatic latent image is developed. That is, an image of yellow toner is formed on the target portion of the photoreceptor 222.

  Subsequently, the target part moves to the position of the image forming unit 3b, and images of magenta toner are formed in an overlapping manner. In the image forming unit 3b, as in the image forming unit 3a, a target portion where an image of yellow toner has already been formed is charged by the charger 31b (step S16). The target portion after charging is irradiated with image forming light from the image forming unit 32b based on the image data indicating the magenta component, and an electrostatic latent image indicating the magenta component is formed (step S17). Then, magenta toner is applied to the electrostatic latent image by the developing device 33b (step S18), and an image of magenta toner is formed on the image of yellow toner.

  The target portion where the image of the yellow and magenta toner is formed continuously moves to a position facing the charger 31c of the image forming unit 3c, and the surface of the target portion is made to be charged by the charger 31c. Charging is performed (step S21). Subsequently, the charged target portion reaches the light irradiation position of the image forming unit 32c, and the charged photosensitive member 222 is irradiated with the image forming light based on the image data indicating the black component.

  FIG. 4 is a diagram showing an example of spectral transmittances of cyan, magenta, and yellow toners. Lines 81, 82, and 83 in FIG. 4 indicate spectral transmittances of cyan, magenta, and yellow toners, respectively. As described above, the wavelength of light from the image forming unit 32c is 700 nm. As shown in FIG. 4, the transmittances of the yellow and magenta toners are 90% or more at the wavelength of 700 nm. Accordingly, even when yellow and magenta toners overlap and adhere to the light irradiation position from the image forming unit 32c at the target portion of the photosensitive member 222, the output of the light source of the image forming unit 32c is output to the image forming unit. Only by making it slightly larger than 32a and 32b, a sufficient amount of light can reach the photosensitive member 222, and an electrostatic latent image showing a black component is stably formed (step S22). .

  Subsequently, the target portion on which the electrostatic latent image is formed on the photosensitive member 222 moves to the position of the developing device 33c, and charged black toner is applied to the surface (step S23). The black toner adheres only to the portion of the photosensitive member 222 where the charge has been removed (ie, the portion irradiated with light) to develop the electrostatic latent image, and overlays the image with yellow and magenta toner. Thus, an image with black toner is formed.

  The target portion after development by the developing device 33c moves to a position facing the charger 31d of the image forming unit 3d, and a charge is applied to the target portion to charge the photosensitive member 222 (step S24). The target portion charged by the charger 31d is irradiated with light based on the image data indicating the cyan component by the image forming unit 32d, and an electrostatic latent image indicating the cyan component is formed (step S25). ). At this time, since the transmittance of the black toner is extremely low in the practical wavelength range of the image forming light, the portion where the black toner is adhered on the photosensitive member 222 (hereinafter referred to as “black region”). The light irradiated onto the photosensitive member 222 does not reach the photosensitive member 222, and the black region on the photosensitive member 222 is hardly neutralized. In addition, since the output of the light source of the image forming unit 32d is increased similarly to the image forming unit 32c, an electrostatic latent image indicating a cyan component is formed with high accuracy outside the black region.

  The target portion of the photosensitive member 222 moves to a position facing the developing device 33d, and cyan toner is applied (step S26). As described above, since the black area on the photosensitive member 222 remains charged, the cyan toner hardly adheres to the black area, and the electrostatic latent image is developed at a portion other than the black area. Is done. That is, an image of cyan toner is formed on the black toner while allowing the cyan toner to overlap the yellow and magenta toners at the target portion on the photoreceptor 222.

  The target portion to which the yellow, magenta, black, and cyan toners are attached moves to a position in contact with the transfer drum 341, and each color toner is transferred to the surface of the transfer drum 341. The toner on the surface of the transfer drum 341 is fixed while being transferred onto the printing paper 9 moving between the transfer drum 341 and the pressure drum 342 according to the rotation of the transfer drum 341, and an image is printed on the printing paper 9. (Step S27).

  The target portion of the photoreceptor 222 that has passed through the transfer mechanism 34 continues to move to the position of the cleaner 35. Then, the cleaner 35 removes unnecessary substances such as toner remaining on the target portion of the photoconductor 222 (that is, toner that has not been transferred to the transfer drum 341) and adhering paper dust, and the surface of the photoconductor 222 is cleaned. The photosensitive member 222 is mechanically returned to the initial state. The cleaned photosensitive member 222 may be neutralized as necessary and electrically returned to the initial state.

  In the printing apparatus 1, the processes in steps S <b> 13 to S <b> 18 and S <b> 21 to S <b> 26 are performed almost in parallel on each part on the photosensitive member 222, and the entire image corresponding to the input image data is placed on the printing paper 9. These processes are continued until printing. When the necessary number of prints are finished, the rotation of the photosensitive drum 22 is stopped (step S28), and the printing process by the printing apparatus 1 is finished.

  As described above, in the printing apparatus 1 shown in FIG. 1, an image is formed on a cyan component having a low light transmittance for image formation after an image of black toner is formed on the photoreceptor 222. When forming an electrostatic latent image showing a black component after forming an image with cyan toner on the photosensitive member 222 as in a conventional printing apparatus, cyan toner adhering to the surface is formed when attempting to achieve high-speed printing. As a result, the light cannot stably reach the photosensitive member 222, and the black toner may adhere unevenly on the cyan toner. On the other hand, in the printing apparatus 1 of FIG. 1, the portion on the photosensitive member 222 to which the black toner is attached is kept charged, so that the cyan toner does not adhere to the black toner.

  If ideal printing is performed according to the image data of each color, the portion where the cyan toner and the black toner overlap on the printing paper is bluish black, but this color is on the cyan toner. It can be said that it is closer to black than the color based on cyan when black toner does not adhere properly. As a result, the printing apparatus 1 can realize stable printing with better color reproducibility than when developing cyan before black. When printing is performed using a tone reproduction method such as halftone dots, it is possible to reproduce bluish black by enhancing cyan.

  Next, an example in which processing suitable for the printing apparatus 1 is performed by the calculation unit 41 of the control unit 4 will be described. The computing unit 41 corrects the cyan image data based on the input image data indicating the black component and the image data indicating the cyan component. Specifically, in step S11 of FIG. 2, light irradiation is turned on based on image data indicating a cyan component in the drawing unit area (pixel at the time of drawing) on the photosensitive member 222 by the calculation unit 41. In addition, a unit region in which the light irradiation is turned on is specified based on the image data indicating the black component. Then, the cyan component image data is corrected (that is, partially deleted) so that light is not irradiated when the electrostatic latent image indicating the cyan component is formed in the specified unit region.

  Subsequently, similarly to the above example, images of yellow, magenta, and black toner are superimposed on the target portion of the photoreceptor 222 (steps S12 to S18, S21 to S23). Thereafter, the target portion is charged by being charged by the charger 31d (step S24), and light is irradiated from the image forming unit 32d to form an electrostatic latent image indicating a cyan component (step S25). At this time, since the image data indicating the cyan component is corrected by the calculation unit 41, a region irradiated with light by the image forming unit 32c (that is, a black region) is not irradiated with light by the image forming unit 32d. The black area is reliably charged. Accordingly, the electrostatic toner image indicating the cyan component is developed without the cyan toner applied by the developing device 33d adhering to the black region (step S26). Then, the toner on the photosensitive member 222 is transferred to the printing paper 9 (step S27), and the printing process is completed by stopping the rotation of the photosensitive drum 22 (step S28).

  As described above, in the printing apparatus 1 using the calculation unit 41, light is not irradiated on the black toner when the cyan electrostatic latent image is formed, and the cyan toner does not adhere to the black toner. . As a result, for example, when the printed image has a large black area, the cyan toner is prevented from unstablely adhering (that is, not adhering) on the black toner, and printing is performed. Further suppression of occurrence of unevenness in the processed image is realized.

  Next, another example of the printing apparatus will be described. In a printing apparatus according to another example, image forming units for yellow, cyan, black, and magenta are sequentially provided in the clockwise direction around the photosensitive drum 22. The image forming unit of each image forming unit is provided with a light source that emits green light having a wavelength of 550 nm.

  In the processing of the printing apparatus according to another example, after an image is formed with yellow and cyan toners, an electrostatic latent image indicating a black component is formed on the photoreceptor 222. Here, FIG. 4 shows the spectral transmittance of a relatively sensitive toner, but the minimum value of the transmittance of a general cyan toner is higher than the line 81 shown in FIG. Therefore, by actually increasing the output of the light source of the image forming unit for black within the usable range, the black component can be reduced even when yellow and cyan toners are adhered on the photosensitive member 222. The electrostatic latent image shown can be formed with high accuracy, and an image of black toner can be formed on the image of yellow and cyan toner.

  Then, an electrostatic latent image indicating a magenta component is formed on the charged photoreceptor 222 without being neutralized by the black toner (and further by processing by the calculation unit 41), and the black toner The electrostatic latent image is developed without (almost) magenta toner adhering to it. Thereby, in the printing apparatus according to another example, it is possible to perform printing at high speed while suppressing the occurrence of unevenness in the image.

  As a practical light source, an LED that emits red or green light is used, but an LED that emits infrared light instead of red may be used, and in the future, blue (for example, An LED that emits light having a wavelength of 450 nm may be used as a light source. In this case, as shown in FIG. 4, since the transmittance for yellow toner is lower than that for cyan and magenta toner, development with black toner and yellow toner are performed after development using cyan and magenta toner. By performing the development in order in order, it is possible to print an image at high speed while suppressing unevenness.

  The example of forming an image with cyan, magenta, or yellow toner after forming an image with black toner on the photoreceptor 222 has been described above. Next, the wavelength of light from the image forming unit and cyan, The relationship with the transmittance of magenta and yellow toner will be described. In the printing apparatus, in consideration of the range in which the output of the light source of the image forming unit can be increased and the allowable range of decrease in the processing capability of the printing apparatus, the exposure amount is increased up to about three times the normal exposure amount. It is possible. Therefore, in order to print an image at a high speed while suppressing unevenness in a printing apparatus, an image of a toner whose color has a light transmittance of 30% or less among cyan, magenta, and yellow is black. It can be said that the toner image is preferably formed after the toner image is formed.

  However, normally, the wavelength of light from each image forming unit is the same, but when including the case where the wavelength of light from each image forming unit is not the same, an electrostatic latent image of a black color component is displayed. The wavelength of light at the time of formation depends on the color of toner developed before black, and the toner developed after black is determined by the color of toner developed before black. More precisely, an image of toner of a color in which light transmittance from a black image forming portion of cyan, magenta, and yellow is 30% or less is formed after an image of black toner is formed. It can be said that it is preferable. Therefore, the following description will be made with attention paid to the wavelength of light from the image forming unit for black.

  In consideration of variations due to the type of toner in the spectral transmittance of FIG. 4, generally, when the wavelength of light from the image forming unit for black is 520 nm or more, an image with cyan toner has a wavelength of When the wavelength is 480 nm or more and 620 nm or less, an image with magenta toner is formed on the image with yellow toner when the wavelength is 500 nm or less. It is possible to perform printing at high speed while suppressing the above. Further, if the transmittance is 20% or less in these wavelength ranges, the occurrence of unevenness in the printed image can be further suppressed as compared with the case of developing black at the end.

  Depending on the wavelength of light from the black image forming unit, the toner of the color having the lowest light transmittance from the black image forming unit among cyan, magenta, and yellow may be superimposed on the black toner image. It may be determined as the toner of the image formed in this way.

  Also, cyan toner has a light transmittance of red or infrared (approximately 600 nm or more), magenta toner has a light transmittance of green (approximately 500 to 600 nm), and yellow toner has blue (approximately) In general, the transmittance of light having a wavelength of 500 nm or less is lowered, so that the light from the image forming unit for black has a wavelength of 600 nm or more (that is, red or infrared). Indicates an electrostatic latent image of the cyan component, an electrostatic latent image of the magenta component when the wavelength is 500 to 600 nm (that is, green), and a yellow latent image when the wavelength is 500 nm or less (that is, blue). It can also be said that the electrostatic latent image of the component is preferably formed after the image is formed with black toner.

  FIG. 5 is a diagram showing the spectral transmittances of the small particle size toner and the large particle size toner. A line 84 in FIG. 5 indicates the spectral transmittance of the small particle size toner, and a line 85 indicates the spectral transmittance of the large particle size toner. Shows the rate. In general, toner having a small particle diameter is thin on the photosensitive member 222 and adheres without gaps, so that the change in transmittance is large and vivid color can be generated as shown in FIG. On the other hand, toner having a large particle size adheres to the photosensitive member 222 with a gap, so that the toner having a small particle size cannot be vividly colored, and the change in transmittance due to the wavelength becomes gentle. In addition, since the toner (wet toner) diffusing in the solvent is less likely to aggregate than the dry toner, the toner having a small particle diameter is usually used as the wet toner.

  By the way, as shown in FIG. 5, in the wavelength band in which the transmittance of the small particle size toner is low, the transmittance is remarkably reduced as compared to the large particle size toner. Therefore, when black is finally developed and high-speed printing is used, if a small-diameter toner is used, there is a high possibility of unevenness in the printed image. However, the printing apparatus according to the present embodiment can print an image with suppressed unevenness at high speed even when the change in transmittance due to wavelength is large, such as a wet toner having a small particle diameter.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  The transfer mechanism 34 does not necessarily have the transfer drum 341 and the pressure drum 342. For example, the toner on the photosensitive member 222 may be transferred onto the printing paper by one drum.

  In the print storage 1, three-color printing or two-color printing may be performed. Even in the case of two-color printing of black and other colors, since the wavelength of light for image formation is usually the same for both color components, other light from the image forming unit for black is used. When the transmittance with respect to the color toner is low, the image formation with the other color toner is performed after the image formation with the black toner.

  The print medium on which the image is printed is not necessarily the printing paper 9, and may be a printing film, for example.

It is a figure which shows the structure of a printing apparatus. It is a figure which shows the flow of the process in which a printing apparatus prints an image on printing paper. It is a figure which shows the flow of the process in which a printing apparatus prints an image on printing paper. It is a figure which shows the spectral transmittance of a toner. It is a figure which shows the spectral transmittance of a small particle size toner and a large particle size toner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printing apparatus 9 Printing paper 31d Charger 32c, 32d Image formation part 33c, 33d Developer 34 Transfer mechanism 41 Calculation part 222 Photoconductor S15-S20 Step

Claims (10)

A printing device,
A first image forming unit that irradiates a charged photosensitive member with light to form a first electrostatic latent image;
A first developer for applying black toner to the first electrostatic latent image on the photoconductor for development;
A charger for applying a charge to the photoreceptor after development by the first developer;
A second image forming unit for forming a second electrostatic latent image by irradiating light to the photoconductor charged by the charger;
The second electrostatic latent image on the photoconductor is developed by applying toner of one color of light of 30% or less from the first image forming portion among cyan, magenta, and yellow toners. A second developing device,
A mechanism for transferring the toner on the photoreceptor to a printing medium;
A printing apparatus comprising: The printing apparatus according to claim 1,
The wavelength of light from the first image forming unit is 520 nm or more;
The printing apparatus according to claim 1, wherein the one color is cyan. The printing apparatus according to claim 1,
The wavelength of light from the first image forming unit is 480 nm or more and 620 nm or less,
The printing apparatus according to claim 1, wherein the one color is magenta. The printing apparatus according to claim 1,
The wavelength of light from the first image forming unit is 500 nm or less;
The printing apparatus according to claim 1, wherein the one color is yellow. The printing apparatus according to any one of claims 2 to 4,
The printing apparatus according to claim 1, wherein a transmittance of light from the first image forming unit of the one color toner is 20% or less. A printing device,
A first image forming unit that forms a first electrostatic latent image by irradiating a charged photoreceptor with red or infrared light;
A first developer for applying black toner to the first electrostatic latent image on the photoconductor for development;
A charger for applying a charge to the photoreceptor after development by the first developer;
A second image forming unit for forming a second electrostatic latent image by irradiating light to the photoconductor charged by the charger;
A second developing device for developing the second electrostatic latent image on the photosensitive member by applying a cyan toner as one color;
A mechanism for transferring the toner on the photoreceptor to a printing medium;
A printing apparatus comprising: A printing device,
A first image forming unit that forms a first electrostatic latent image by irradiating a charged photoreceptor with green light;
A first developer for applying black toner to the first electrostatic latent image on the photoconductor for development;
A charger for applying a charge to the photoreceptor after development by the first developer;
A second image forming unit for forming a second electrostatic latent image by irradiating light to the photoconductor charged by the charger;
A second developing device for developing the second electrostatic latent image on the photosensitive member by applying a magenta toner of one color;
A mechanism for transferring the toner on the photoreceptor to a printing medium;
A printing apparatus comprising: The printing apparatus according to any one of claims 1 to 7,
The second image data is corrected based on the first image data indicating the black component of the image to be printed and the second image data indicating the component of the one color, and light is emitted from the first image forming unit. The printing apparatus further includes a calculation unit that sets a region on the photosensitive member as a non-irradiation region of light by the second image forming unit. The printing apparatus according to any one of claims 1 to 8,
A printing apparatus, wherein the toner used for development is a wet toner. A printing method for printing an image,
Irradiating the charged photoreceptor with light from the first image forming unit to form a first electrostatic latent image;
Applying black toner to the first electrostatic latent image on the photoconductor and developing the first electrostatic latent image;
Applying a charge to the photoconductor after development and charging;
Irradiating the charged photoreceptor with light from a second image forming unit to form a second electrostatic latent image;
The second electrostatic latent image on the photoconductor is developed by applying toner of one color of light of 30% or less from the first image forming portion among cyan, magenta, and yellow toners. And the process of
Transferring the toner on the photoreceptor to a printing medium;
A printing method comprising:

Images